We had a bathroom built in our basement. The inspector told me the pump was huge and overkill for the one bathroom but it passed. When you're in the shower you here a loud bang that sounds like someone banged on the wall really loud. Went around to the pump and when the water runs for a while you here it swish through the pipes all at one and then there is a loud bang that actually shakes the wall that the shower is on. Is this normal? I am worried since I fired my contractor for numerous reasons including using an unlicensed plumber.

Hi She4

Well, to a point, it is very normal. Here, what you hear is the CHECK VALVE flapper falling back into place once the waste has been pumped up. The check valve keeps the sewage that gets pumped up from falling back into the ejector pit, so it is needed and unfortunately they can be noisy.

Alternatives in this case could be to have the check valve installed higher up the pipe... higher usually equals less noise, installing the check valve on a horizontal section of the pump discharge line (properly oriented) could also help reduce the noise, and finally, another alternative would be to have your clunky check valve replaced with the SILENCER check valve.

Check thesilencer check valve out @ 2" Silencer Sump Pump Check Valve - True Union Swing | Plumbsource.net

I attached a picture below for reference.

Hope that helped. Let me know if you have questions, OK?

Mark